Systems and methods for real-time monitoring of micromilling tool wear

ABSTRACT

The wear status of a micro-endmill tool may be inferred by monitoring the chip production rate of the tool in operation. Chips may be extracted from a work area, captured on an adhesive surface, imaged, and counted to determine the chip production rate. When the rate of chip production falls, the feed rate of the micro-endmill may be increased to a level suitable for the current state of tool wear. In this manner, costly and inconvenient work stoppages to evaluate the wear status of a tool are eliminated.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of PCT Application No.PCT/US2015/014848 filed on Feb. 6, 2015 and entitled “SYSTEMS ANDMETHODS FOR REAL-TIME MONITORING OF MICROMILLING TOOL WEAR”. PCTApplication No. PCT/US2015/014848 claims priority to, and the benefitof, U.S. Provisional Application Ser. No. 61/936,607 filed on Feb. 6,2014 and entitled “SYSTEMS AND METHODS FOR REAL-TIME MONITORING OFMICROMILLING TOOL WEAR.” Both of the above applications are herebyincorporated by reference in their entirety.

TECHNICAL FIELD

The present disclosure relates to micromilling, and in particular tomonitoring of tool wear in connection with the same.

BACKGROUND

Micromilling is a material-removal manufacturing process for producingparts that typically are less than 1 mm in size, with features measuredin microns, and sub-micron manufacturing tolerances. A micromillingmachine typically consists of a tool known as a micro-endmill placed ina spindle. The micro-endmill contains one or more teeth. The spindletypically rotates the micro-endmill at speeds exceeding 50,000 RPM whileadvancing the tool through the material. Each time a tooth of themicro-endmill passes through the material, a chip is produced andremoved from the material. As the micro-endmill removes chips, the teethbecome dull. Dull micro-endmill teeth cause a manufacturing defect knownas “burring” and eventually cause the micro-endmill to break.

Measuring the state of wear of a micro-endmill is typically done byhalting the cutting process, removing the micro-endmill from themachine, and examining it under a microscope. The radius of the cuttingedge of the teeth is measured visually, and is used as a quantificationof tool wear. This process is cumbersome and time-consuming;accordingly, improved systems and methods for assessing tool wear aredesirable.

SUMMARY

In an exemplary embodiment, a tool wear monitoring system comprises askirt couplable to a micro-endmill to contain chips produced duringoperation of the micro-endmill. The system further comprises a tubecoupled to the skirt, the tube configured to extract air from the skirtand carry the chips to a nozzle. The system further comprises anadhesive tape disposed at an outlet of the nozzle to catch chips exitingthe nozzle, a conveyor belt to move the adhesive tape into the field ofview of a camera, the camera operative to obtain images of the chips onthe adhesive tape, and a software program operative on a computingdevice to count the chips from the images.

In another exemplary embodiment, a method for monitoring wear of amicromilling tool comprises determining an initial chip production rate;extracting, via a skirt, tube, and pump, chips produced during operationof the micromilling tool; depositing, from a nozzle coupled to the tube,the chips on adhesive tape; moving, via a conveyor belt, the adhesivetape to bring the chips into the field of view of a camera; acquiring,via the camera, an image of the chips; counting, by an image processingsystem, the chips in the image to determine a current chip productionrate; and calculating, using the initial chip production rate and thecurrent chip production rate, the wear status of the micromilling tool.

In another exemplary embodiment, a method of counting chips produced bya micro-endmill comprises obtaining, by a system for monitoring toolwear, an image of chips captured by adhesive tape; converting the imageto grayscale; thresholding the image to remove excessive lustre;equalizing a histogram of the image to improve contrast; thresholdingthe image to identify a background grayscale level; converting the imageto black and white; eroding the image to reduce pixelated errors;performing edge detection on the image to form edges therein; performingdilation on the image to connect at least a portion of the edges;filling the image components arising from the edge detection; andcounting the chips appearing in the image.

BRIEF DESCRIPTION OF THE DRAWINGS

With reference to the following description and accompanying drawings:

FIG. 1 illustrates a block diagram of an exemplary micromilling toolwear monitoring system in accordance with an exemplary embodiment;

FIG. 2 illustrates a block diagram of exemplary components of amicromilling tool wear monitoring system in accordance with an exemplaryembodiment;

FIG. 3 illustrates an exemplary micromilling tool wear monitoring systemin accordance with an exemplary embodiment;

FIG. 4A illustrates an exemplary method for processing images inconnection with use of a micromilling tool wear monitoring system inaccordance with an exemplary embodiment;

FIGS. 4B through 4J illustrate image processing steps in an exemplarymethod for processing images in connection with use of a micromillingtool wear monitoring system in accordance with an exemplary embodiment;

FIG. 5A illustrates chip production over time in accordance with anexemplary embodiment; and

FIG. 5B illustrates a method for monitoring micromilling tool wear inaccordance with an exemplary embodiment.

DETAILED DESCRIPTION

The following description is of various exemplary embodiments only, andis not intended to limit the scope, applicability or configuration ofthe present disclosure in any way. Rather, the following description isintended to provide a convenient illustration for implementing variousembodiments including the best mode. As will become apparent, variouschanges may be made in the function and arrangement of the elementsdescribed in these embodiments without departing from the scope of thepresent disclosure.

For the sake of brevity, conventional techniques for machining,micromilling, microscopy, and/or the like may not be described in detailherein. Furthermore, the connecting lines shown in various figurescontained herein are intended to represent exemplary functionalrelationships and/or physical couplings between various elements. Itshould be noted that many alternative or additional functionalrelationships or physical connections may be present in a practical toolwear monitoring system.

In accordance with principles of the present disclosure, tool wear maybe monitored during the cutting process via measuring the rate of chipproduction. The “minimum chip thickness” principle indicates that atooth cannot produce a chip that is thinner than ⅓ of the cutting edgeradius of that tooth. Accordingly, principles of the present disclosurecontemplate real-time monitoring of the state of wear of amicro-endmill; this may be accomplished by recognizing the existence ofa relationship between the state of tool wear and a discrepancy betweenthe number of chips that should be produced (based, for example, onmachining parameters) and the number of chips that are actuallyproduced. An exemplary tool wear monitoring system may be configured tomeasure this discrepancy and thus infer the state of tool wear.

As opposed to prior approaches, principles of the present disclosureenable monitoring of micro-scale tool wear without halting the cuttingprocess, and thus enable measurement of micro-scale tool wear rates.Machining parameters may be adjusted according to the amount of toolwear. Additionally, principles of the present disclosure enableprevention of micro-scale tool wear-related defects such as burring andtool breakage.

A tool wear monitoring system may be any system configured to facilitatedetection or inference regarding the wear state of a milling tool. In anexemplary embodiment, with reference to FIGS. 1, 2, and 3, a tool wearmonitoring system 100 comprises a pneumatic component 120, an adhesioncomponent 140, an imaging component 160, and a control component 180.Pneumatic component 120 is configured to extract chips created during amilling process from the work area, and deliver the chips elsewhere forevaluation. Adhesion component 140 is configured to secure and/ordeliver the chips for evaluation. Imaging component 160 is configured toassess and evaluate the chips, and consequently determine and/or inferthe wear state of a tool. Control component 180 is configured to providefeedback and/or control to a system or portions thereof, for example amicromilling machine, responsive to the determination of the wear stateof a tool. Components of tool wear monitoring system 100 may bephysically, electrically and/or communicatively coupled to one another,for example at least partially via wired or wireless communication links190.

In various exemplary embodiments, tool wear monitoring system 100 isconfigured to allow for real-time assessment of the rate of chipproduction in a micromilling machine 101 as operative on a workpiece105. Using information from the minimum chip thickness effect, tool wearcan be inferred.

In an exemplary embodiment, with reference to FIGS. 2 and 3, pneumaticcomponent 120 comprises skirt 122, tubing 124, pump 126, and nozzle 128.In various exemplary embodiments, skirt 122 is configured to be fittedaround and/or coupled to micro-endmill 102, for example as illustratedin FIG. 3. Skirt 122 functions as a physical containment or funnelingelement to contain chips as they are produced and cause the chips to becaught in an airflow stream through tubing 124. In an exemplaryembodiment, skirt 122 comprises a 0.75 inch diameter transparent plasticsuction cup having a height of about 0.5 inch. However, skirt 122 maycomprise any suitable material and dimensions configured to containchips produced by micro-endmill 102. A hole of suitable diameter, forexample between about 0.05 inches and about 0.15 inches, and preferablyabout 0.08 inches, is punched through the side of skirt 122 tofacilitate coupling with tubing 124. Skirt 122 is coupled tomicro-endmill 102 such that the bottom of the skirt is positioned fromabout 0.5 mm to about 1 mm above the tip of the endmill; in other words,when micro-endmill 102 is operative, a gap of between about 0.5 mm andabout 1 mm exists between the bottom of skirt 122 and the surface ofworkpiece 105. This provides sufficient clearance for air to be pulledinto the interior of skirt 122, but maintains a sufficient pressuredifferential between the exterior and the interior of skirt 122 so thatchips are not allowed to leave the interior of skirt 122.

Tubing 124 is coupled to skirt 122. Tubing 124 is configured to providevacuum extraction of the air and chips contained by skirt 122. Tubing124 may comprise polyethylene or other suitable strong and/or flexiblematerial. Additionally, polyethylene provides resistance to staticelectricity and thus reduces the likelihood of chips becoming stuck intubing 124; moreover, polyethelyne is sufficiently hard enough toprevent chips from becoming embedded in the interior wall of the tubeand is also resistant to kinking.

In various exemplary embodiments, tubing 124 is configured with an innerdiameter of between about 0.1 inches and about 0.25 inches, andpreferably about 0.125 inches, in order to provide a suitable airflowvelocity and room for movement of chips therethrough.

Tubing 124 is coupled to pump 126. Pump 126 supplies vacuum pressure toextract chips from the interior of skirt 122 by way of tubing 124. Inorder to ensure accurate chip rate production calculations, pump 126 isdesirably selected such that no chips can be lodged in the interiorduring operation and dislodged at a later time during operation. Thus,in various exemplary embodiments, pump 126 comprises a vacuum pumpoperative on the venturi principle and having no moving parts in theinterior of the pump. Rather, the vacuum force is created by apressurized air input. In one exemplary embodiment, pump 126 comprises aVaccon DF 1-3 venturi suction pump. In this exemplary embodiment, pump126 provides a static vacuum of approximately 12″ Hg (400 mbar) at 100psi (7 bar) supply pressure; corresponding air consumption isapproximately 100 lpm (liters per minute). However, any suitable pump126 may be utilized, as desired.

Tubing 124 is coupled to nozzle 128. Tubing 124 and nozzle 128 may beseparate components; alternatively, tubing 124 and nozzle 128 may bemonolithic; i.e., tubing 124 may widen at one end into a sectionconsidered to be nozzle 128. In various exemplary embodiments, nozzle128 has an inner diameter twice that of tubing 124. In other exemplaryembodiments, nozzle 128 has an inner diameter four times that of tubing124. Moreover, nozzle 128 may be configured with any suitable innerdiameter configured to provide sufficient airflow slowing as compared tothe flow speed in tubing 124, in order to ensure adhesion of chips inconnection with adhesion component 140. This relationship in tubingdiameters is important in order to increase the air velocity where thechips are being pulled into the air stream at skirt 122, and to decreasethe air velocity where the chips are being pushed out of the air streamvia nozzle 128 onto tape 144. Increasing the air speed at tubing 124inlet helps to prevent chip loss at the inlet due to chip scatter fromthe spindle, while decreasing air speed at nozzle 128 outlet helpsprevent chip loss due to air dispersion. A four-fold increase in theinner diameter between tubing 124 and nozzle 128 results in anapproximately sixteen-fold decrease in airflow velocity at the outlet ofnozzle 128.

Nozzle 128 disperses chips from tubing 124 onto tape 144. Nozzle 128functions to prevent chips from being lost (that is, blown into theenvironment rather than adhered to tape 144) and to roughly equallydisperse chips across the width of tape 144 within the field-of-view ofcamera 162. In order to minimize chip dispersion, the end of nozzle 128may desirably be placed between about 0.1 inches and about 0.25 inches,and preferably about 0.125 inches, above the surface of tape 144.

Pneumatic component 120 may be powered as suitable, for example by asingle pressured airline that provides pressure for pump 126 and for thecooling system of the spindle of micromilling machine 101. Duringoperation of pneumatic component 120, airstream velocity at the inlet oftubing 124 is desirably between about 150 meters per second (m/s) andabout 250 m/s, and preferably about 210 m/s, when tubing 124 isconfigured with an inner diameter of 0.125 inches. Additionally,airstream velocity at the outlet of nozzle 128 is desirably below 20 m/swhen nozzle 128 is configured with an inner diameter of about 0.5inches. In this manner, chips are effectively collected from withinskirt 122 and delivered and adhered to tape 144.

In various exemplary embodiments, adhesion component 140 comprises belt142 and tape 144. Belt 142, for example a conveyor belt, operates as abase to move a strip of tape 144 material past nozzle 128 and thereafterpast camera 162. Tape 144 operates to collect and secure chips exitingnozzle 128.

Belt 142 may comprise any suitable conveyor belt or similar device. Invarious exemplary embodiments, belt 142 may be configured with asuitable and/or adjustable belt speed, for example a speed range ofbetween about 0.5 meters per minute (m/m) to about 20 m/m. Additionally,belt 142 may be configured with a suitable belt color to reduce imageglare and provide contrast for chips (for example, for dark chips, amatte white belt color is desirable, while for lighter colored chipssuch as aluminum, a matte black belt color may be desirable). Belt 142may be configured with a multicolor or striped belt in order to allowtape 144 to be moved back and forth thereon to a suitable backgroundcolor for the currently produced chips, as desired.

Tape 144 may comprise any suitable tape configured to be deliverable viabelt 142 and capable of retaining chips. In various exemplaryembodiments, tape 144 has a weak adhesive on one side and a strongadhesive on the other side. The roll of tape 144 is positioned so thatthe weak adhesive makes contact with belt 142 and the strong adhesivefaces towards nozzle 128. As belt 142 moves, the friction force of theweak adhesive against belt 142 pulls tape 144 off of the tape sourcingroll onto belt 142. Tape 144 may be configured with any suitabledimensions; however, in various exemplary embodiments, tape 144 isconfigured with a width approximately twice that of the inner diameterof nozzle 128 so that chips may be fully captured on tape 144. Tape 144may be selected to be generally transparent, translucent, and/or opaque,as desired, depending on the color of belt 142 and in order to providesuitable imaging contrast with chips.

Once chips are secured on tape 144, the chips are advanced via belt 142to camera 162. Camera 162 may comprise any suitable image capturedevice. In one exemplary embodiment, camera 162 comprises a Dino-Litebrand digital universal serial bus (USB) microscope. Camera 162 may bemounted on an adjustable mounting bracket to allow for greaterfunctionality of the camera as well as initial focusing. Camera 162 maybe configured with a field of view at least as wide as the width of tape144 in order to obtain suitable images for evaluation (i.e., in order toensure that chips captured on tape 144 do not fall outside the field ofview). Camera 162 takes images of tape 144 and chips captured thereon,for example at regular intervals or on demand. When camera 162 isacquiring an image, belt 142 is desirably paused, for example via asignal from image processing system 166, in order to minimize motionblurring. Belt 142 thereafter returns to motion.

Lighting system 164 provides illumination to chips captured on tape 144as they pass through the field of view of camera 162. Lighting system164 may comprise any suitable component or component for providingbright diffuse lighting as is known in the art.

Image processing system 166 receives images from camera 162 andprocesses them to identify and count individual chips. Image processingsystem 166 may comprise any suitable hardware and/or softwarecomponents. In one exemplary embodiment, image processing system 166comprises a laptop personal computer having technical computing softwaresuch as Matlab operative thereon. Additionally, it will be understoodthat in certain exemplary embodiments, image processing system 166 andtool control component 180 may all be operative on and/or comprisehardware and/or software components of a single system, for example alaptop personal computer, desktop computer, tablet, smartphone, and/orthe like.

In various exemplary embodiments, control system 180 is configured tocontrol one or more of micromilling machine 101, pump 126, belt 142,camera 162, and/or image processing system 166. For example, responsiveto image processing system 166 determining that the rate of chipproduction has fallen below a threshold, control system 180 may send asignal to micromilling machine 101 to increase the feed rate. Moreover,control system 180 may control the interval of image acquisition bycamera 162, the speed and/or starting/stopping of belt 142, and anyother suitable aspects of tool wear monitoring system 100.

With reference now to FIGS. 4A-4J, in various exemplary embodiments amethod 400 for counting chips comprises acquiring a digital image fromcamera 162 (step 405, illustrated in FIG. 4B). The image is converted tograyscale (step 410). Thresholding is performed to remove excessivelustre (step 415, illustrated in FIG. 4C). Histogram equalization isperformed to improve contrast (step 420, illustrated in FIG. 4D).Thresholding is performed to find the grayscale background level (step425, illustrated in FIG. 4E) and the image is converted to black andwhite (step 430, illustrated in FIG. 4F). Erosion is performed to reducepixelated errors (step 435, illustrated in FIG. 4G). Edge detection isperformed (step 440, illustrated in FIG. 4H), and dilation is performedto connect edges and close components (step 445, illustrated in FIG.4I). Components are filled (step 450, illustrated in FIG. 4J) and thencounted (step 455).

Turning now to FIG. 5B, in an exemplary embodiment a method 500 formonitoring micromilling tool wear comprises obtaining a chip countresulting from operation of a micro-endmill (step 510). The chip countis compared to a target chip count (step 520), for example a target chipcount equal to a chip count that would be expected if the micro-endmillwere operating at the expected tooth-passing rate. If the differencebetween the chip count and the target chip count exceeds a threshold,the feed rate may be adjusted (step 530), for example increased, inorder to increase the chip production rate. The process is repeated, asdesired, in order to regularly monitor the chip count and/or adjust thefeed rate. In one exemplary embodiment, the threshold for the differencebetween the target chip count and the chip count is a decrease ofbetween about 40% and about 60%. Moreover, a suitable threshold may beselected based on the understanding that chip production typically goesfrom a level X to about a level X/2 as the tool wears, representingslippage of approximately every other tooth in the micro-endmill tool.

The foregoing exemplary embodiments have presented airflow-drivenextraction of chips. It will be appreciated that principles of thepresent disclosure are also applicable to fluid-driven extraction ofchips, for example via cutting fluid. In these exemplary embodiments,cutting fluid may be directed over and/or around workpiece 105 and thenextracted together with the resulting chips; the cutting fluid and chipmixture may be thereafter passed through a generally planar plasticenclosure to permit photographing/counting of the chips therein.

In tool wear monitoring system 100, the rate at which chips pass bycamera 162 may be compared to the expected tooth-passing rate ofmicro-endmill 102. If the chip production rate is equal to thetooth-passing rate, then the tool cutting-edge radius is less than thatcalculated by the minimum chip thickness equation. Similarly, if thechip production rate drops below the tooth-passing rate, then the toolcutting-edge radius is known to be equal to that calculated by theminimum chip thickness equation.

In an exemplary embodiment, the feed rate and spindle speed ofmicromilling machine 101 are initially set so that the chip productionrate is equal to the tooth passing rate. The chip production rate isthen observed until the chip production rate drops below the toothpassing rate. FIG. 5A shows an example plot of chip production rate withtime as will be observed in this process. Times and chip production ratevalues are labeled, and will be referred to in the following equations.

At the beginning of the tool-wear measuring operation (prior to timeT1), the feed rate f0 is set according to Eq. (1), where re0 is theinitial cutting-edge radius of the cutting tool, before cutting begins,n is the number of teeth on the cutter, N is the spindle speed, and δ isa small value, perhaps 1% of the value calculated if δ is zero.

f0=0.3*re0*n*N+δ  (Equation 1)

The initial chip production rate C0 will be equal to the tooth passingrate, as shown in Eq. (2).

C0=n*N  (Equation 2)

The chip production rate is measured by tool wear monitoring system 100.At some future time T2, the chip production rate is observed todecrease. At that time, the amount of tool wear re1 at the previous timeT1 can be calculated according to Eq. (3).

re1=f0/(0.3*n*N)  (Equation 3)

At time T3, the feed rate is increased to the value f1, calculated as inEq. (4).

f1=0.3*re1*n*N+δ  (Equation 4)

When the feed rate is increased to value f1, the chip production ratewill rise back to C0 and become constant. The tool's continued wear willcause the chip production rate to drop again, detected at time T5. Atthat time, the amount of tool wear re2 at time T4 can be calculatedaccording to Eq. (5).

re2=f1/(0.3*n*N)  (Equation 5)

At time T6, the feed rate is increased to the value f2, calculated as inEq. (6).

f2=0.3*re2*n*N+δ  (Equation 6)

Generalizing, at each future time T_(i+1) that the chip production rateis observed to drop below the value C0, the amount of tool wear rei atthe previous time T_(i) is calculated according to Eq. (7), and the feedrate is increased to the value fi as in Eq. (8).

rei=fi−1/(0.3*n*N)  (Equation 7)

fi=0.3*rei*n*N+δ  (Equation 8)

This process may be continued until the tool breaks and/or is otherwisereplaced. The tool wear rate is given by the values of rei at the timesT_(i) as i varies from 0 until the tool breaks. In various exemplaryembodiments, C1 is approximately half the value of C0, representingslippage of approximately every other tooth in micro-endmill 102.

While the principles of this disclosure have been shown in variousembodiments, many modifications of structure, arrangements, proportions,the elements, materials and components, used in practice, which areparticularly adapted for a specific environment and operatingrequirements may be used without departing from the principles and scopeof this disclosure. These and other changes or modifications areintended to be included within the scope of the present disclosure.

The present disclosure has been described with reference to variousembodiments. However, one of ordinary skill in the art appreciates thatvarious modifications and changes can be made without departing from thescope of the present disclosure. Accordingly, the specification is to beregarded in an illustrative rather than a restrictive sense, and allsuch modifications are intended to be included within the scope of thepresent disclosure. Likewise, benefits, other advantages, and solutionsto problems have been described above with regard to variousembodiments. However, benefits, advantages, solutions to problems, andany element(s) that may cause any benefit, advantage, or solution tooccur or become more pronounced are not to be construed as a critical,required, or essential feature or element.

As used herein, the terms “comprises,” “comprising,” or any othervariation thereof, are intended to cover a non-exclusive inclusion, suchthat a process, method, article, or apparatus that comprises a list ofelements does not include only those elements but may include otherelements not expressly listed or inherent to such process, method,article, or apparatus. Furthermore, no element, component, or methodstep in the present disclosure is intended to be dedicated to the publicregardless of whether the element, component, or method step isexplicitly recited in the claims. No claim element herein is to beconstrued under the provisions of 35 U.S.C. §112(f), unless the elementis expressly recited using the phrase “means for.” Also, as used herein,the terms “coupled,” “coupling,” or any other variation thereof, areintended to cover a physical connection, an electrical connection, amagnetic connection, an optical connection, a communicative connection,a functional connection, and/or any other connection.

When language similar to “at least one of A, B, or C” or “at least oneof A, B, and D” is used in the claims, the phrase is intended to meanany of the following: (1) at least one of A; (2) at least one of B; (3)at least one of C; (4) at least one of A and at least one of B; (5) atleast one of B and at least one of C; (6) at least one of A and at leastone of C; or (7) at least one of A, at least one of B, and at least oneof C.

What is claimed is:
 1. A tool wear monitoring system, comprising: askirt couplable to a micro-endmill to contain chips produced duringoperation of the micro-endmill; a tube coupled to the skirt, the tubeconfigured to extract air from the skirt and carry the chips to anozzle; an adhesive tape disposed at an outlet of the nozzle to catchchips exiting the nozzle; a conveyor belt to move the adhesive tape intothe field of view of a camera; the camera operative to obtain images ofthe chips on the adhesive tape; and a software program operative on acomputing device to count the chips from the images.
 2. The system ofclaim 1, wherein the computing device is configured to vary the feedrate of the micro-endmill responsive to the chip count.
 3. The system ofclaim 1, wherein the computing device is configured to pause operationof the conveyor belt when the camera acquires an image of the chips onthe adhesive tape.
 4. The system of claim 1, wherein the outlet of thenozzle has an inner diameter at least four times larger than the innerdiameter of the tube at the location the tube is coupled to the skirt.5. The system of claim 1, wherein a bottom of the skirt is disposedwithin 1 mm of a workpiece in order to provide airflow into the interiorof the skirt while still containing chips produced within the skirt. 6.The system of claim 1, wherein the airspeed in the tube at the locationwhere the tube couples to the skirt exceeds 200 meters per second. 7.The system of claim 1, wherein the airspeed at an exit of the nozzle isless than 15 meters per second.
 8. The system of claim 1, wherein thewidth of the adhesive tape is at least twice the inner diameter of thenozzle.
 9. The system of claim 1, further comprising a vacuum pump tocause air to flow into the tube from the skirt.
 10. A method formonitoring wear of a micromilling tool, the method comprising:determining an initial chip production rate; extracting, via a skirt,tube, and pump, chips produced during operation of the micromillingtool; depositing, from a nozzle coupled to the tube, the chips onadhesive tape; moving, via a conveyor belt, the adhesive tape to bringthe chips into the field of view of a camera; acquiring, via the camera,an image of the chips; counting, by an image processing system, thechips in the image to determine a current chip production rate; andcalculating, using the initial chip production rate and the current chipproduction rate, the wear status of the micromilling tool.
 11. Themethod of claim 10, further comprising adjusting, responsive to thecalculating the wear status, a feed rate associated with themicromilling tool.
 12. A method of counting chips produced by amicro-endmill, the method comprising: obtaining, by a system formonitoring tool wear, an image of chips captured by adhesive tape;converting the image to grayscale; thresholding the image to removeexcessive lustre; equalizing a histogram of the image to improvecontrast; thresholding the image to identify a background grayscalelevel; converting the image to black and white; eroding the image toreduce pixelated errors; performing edge detection on the image to formedges therein; performing dilation on the image to connect at least aportion of the edges; filling the image components arising from the edgedetection; and counting the chips appearing in the image.